Machines for the stringing of tennis rackets



} May. 12, 1970 I I R. SIIPENLIEIV 3,51 2

; MACHINESTOR THE STRINGING OF TENNIS RACKE'I'S Filed Feb; 8, 1968 j v v 3 Sheets-Sheet 1 ffi; SPQNLE' 1 MACHINES FOR THE sTfimGING OF TENNIS BACKE'IS I Filed Feb. 8,1968

3 Sheets Sheet 2 IRSPENLE May 12, 1970 MACHINES FOR THE STRINGING OF TENNIS RACKETS 3 Shecs-Sheet 3 Filed Feb. 8, 1968 iii!!! 3 United States Patent 8,320 Int. Cl. A63b 51/14 U.S. Cl. 273-73 6 Claims ABSTRACT OF THE DISCLOSURE The frame of the racket to be strung is mounted on a cradle rotatable about a vertical axis and the machine comprise means to tension thestring threaded through a pair of perforations of the racket frame to form one element of the stringing. The cradle carries an adjustable clamping device disposed below the racket frame and which may act on the said element close to the frame to maintain same under tension, whereby the string may be released from the tensioning means, threaded through another pair of perforations to form the next element and again tensioned after the cradle has been rotated through 180.

This invention relates to machines used for the stringing of tennis rackets.

The known stringing machines generally comprise a swinging counterweight mechanism adapted to tension the string which has just been passed through a pair of corresponding perforations of the racket frame in order to form one of the elements of the stringing (longitudinal or vertical elements and transverse or horizontal elements), while there is provided a clamping device which may clamp the string within the racket frame (i.e. the element being realized) close to the outlet perforation of the string (i.e. the perforation through which the free portion of the string issues from the frame). Once the element forming portion of the string is thus clamped and retained under tension, the free portion thereof may be released from the tensioning counterweight mechanism and passed through another pair of perforations of the racket frame. The cradle which supports the racket frame is then rotated through 180 in order that the outlet perforation of the next stringing element may be situated in front of the counterweight mechanism and the operative cycle is repeated. The clamping device must of course be disposed near the opposite side of the racket frame.

In the known machines this clamping device is adjustably carried by a frame disposed above the cradle which supports the frame of the racket. This position is an important dra'wback since the clamping device and its supporting frame hinder free access to the racket frame, more particularly when the operator has to dispose the horizontal or transverse elements which are to for the stringing of tennis rackets, of the kind comprising a rotatable cradle on which the frame of the racket to be strung is fixed, means for tensioning the string from which the stringing is to be made each time the said string has been threaded through a pair of perforations of the racket frame in order to form an element of the stringing, and a clamping device for retaining under tension each element of the stringing while the string is 3,511 ,502 Patented May 12, 1970 ice being threaded through another pair of perforations of the said racket frame in order to form another element of the stringing, the clamping device is carried by an adjustable support disposed below the racket frame mounted on the cradle, so as to leave free access to the said frame during the stringing operation.

In the accompanying drawings:

FIG. 1 is a view in elevation of a stringing machine according to the invention, the parts being shown after the string has been threaded through a pair of perforations of a racket frame and has just been tensioned in order to form a first vertical element of the stringing.

FIG. 2 is a fragmental plan view corresponding to FIG. 1.

FIG. 3 is a view in elevation of the upper portion of the'machine the vertical element being clamped by the clamping device and the string being released from the tensioning device.

FIG. 4 is a fragmental plan view corresponding to FIG. 3, but showing the parts after the cradle has been rotated through FIG. 5 is a fragmental plan view similar to FIG. 4, but showing the string threaded through another pair of perforations of the racket frame and submitted to the action of the tensioning device.

FIG. -6 is an axial section of the lower central portion of the cradle.

FIG. 7 is a view in elevation with parts in section showing the clamping device in the open condition.

FIG. 8 is a view similar to FIG. 7, but with the parts illustrated in the closed condition of the clamping device.

FIG. 9 is a section taken through line IX-IX of FIG. 8.

Referring to FIG. 1 the machine comprises a vertical frame 1 which supports a horizontal table 2. A base member 3 carried by table 2 is formed at one of its ends with an upstanding portion 3a on which a tensioning device is mounted. The latter comprises a sector-shaped member 4 extending substantially through 180 and which is rotatably supported by a pin 3b secured to the upstanding portion 3a. A guide 5 and a drum 6 are secured to the sector-shaped member 4, the axis of the guide being substantially parallel to the axis of pin 3b while the axis of the drum is substantially radial thereto. The outer end of the said sector shaped member 4, carries a string retaining mechanism generally designated by reference numeral 7, this mechanism comprising a fixed jaw 7r: secured to member 4 and a movable jaw 7b pivoted to the member 4 at 4a and formed with an actuating extension 7c on which is hinged the upper end of a driving rod 8. The lower end of this rod carries a flat lug 9 which is pivoted at 10a on an arm 10. As shown this arm 10 is rotatably supported at 1a by the frame 1 and it carries a counterweight 11 which is preferably adjustable in position. Arm 10 may be raised by means of a flexible cable 12 which passes on a loose pulley 13 supportedby the lower side of table 2, its end being attached to an appropriate actuating pedal (not shown). It is thus possible to raise the arm 10 by means of this pedal in order to release the string retaining mechanism 7.

At its end opposed to the upstanding portion 3a the base 3 is formed with a substantially circular boss 30 (FIG. 6). A vertical shaft 14 is rotatably mounted'in this boss 3c, as by means of anti-friction bearings, the

upper end of the said shaft carrying a flat cylindrical proper direction support may be locked at any angular position desired.

The flat cylindrical support 15 has two diametrically opposed arms 19 which are secured thereto in any appropriate manner, as by welding. These arms are upturned, as shown in FIGS. 1 and 3 and each carries at its upper end an arcuate extension 19a situated in a horizontal plane, these extensions opening towards each other. Support 15, arms 19 and extension 19a thus form a cradle to which the frame of the racket to be strung may be secured. It will be noted that this cradle is somewhat resilient and may be elastically deformed to a slight extent during the stringing operation. The racket frame may be maintained on the cradle by means of the usual clamps 20, as indicated in FIGS. 1 and 3. As shown in dash-and-dot lines in FIGS. 2, 4 and 5, the ratchet frame is disposed with its major axis substantially parallel to the common axis of the horizontal portions of arms 19.

The upper side of the fiat cylindrical support .15 (FIG. 6) carries an axial pin 21 on which is loosely mounted a horizontal arm 22 which may be locked in position by means of a nut 23 screwed on the threaded upper end of pin 21, this nut being provided with any kind of manual actuating member, such as a transverse bar, as shown. As indicated in FIG. 6, the portion of pin 21 on which arm 22 is mounted is of smaller diameter than the threaded upper up of the said pin and it may slide in an axially elongated aperture 22a (FIG. 2) provided in the arm, this aperture being of button-hole shape, i.e. having at one of its ends and enlarged portion through which the threaded upper end of pin 21 may pass. Owing to this arrangement arm 22 may slide longitudinally on pin 21 and it may rotate with respect thereto without any exaggerated clearance.

This arm 22 carries at one of its ends a vertical socket 24 (FIG. 1) in which is pivotally and slidably mounted the tubular lower end of the support 25 of a clamping device. As shown in FIGS. 7 and 9, the upper end of support 25 is in the form of an upwardly opening fork. To the inner side of one of the branches of this fork is secured a fiat member 26 the upper edge of which is integral with a number of downwardly bent fingers 26a adapted to form the fixed jaw of the clamping device. This fixed jaw cooperates with a movable jaw comprised of a number of flat vertical teeth 27a, each adapted to engage the hook-like bent portion of a finger 26a, as best shown in FIG. 9. Teeth 27a are formed along the upper edge of a plate 27 adapted to slide against the flat member 26. Plate 27 is integral with a rod-like guiding tail 27b which is axially slidable in support 25. Plate 27 also carries a transverse pin 27c on which is hinged an actuating lever 28. The latter is pivoted at 28a to one end of a link 39. The other end of link 39 is hinged on a pin 30a eccentrically carried by a gudgeon 30 which may be locked at any suitable angular position in support 25, as for instance by a set screw (not shown).

It will be understood that when lever 28 is swung about pin 27c, plate 27 is deplaced vertically on member 26, the latter being formed for this purpose with a vertical guiding groove in which the protruding end of pin 27c may slide. The movable teeth 27a may thus slide into the bent portion of fingers 26a in order to clamp a string previously disposed in the said portion. When the axes of 'pins 27c, 28d and 30a are substantially in one and the same plane, fingers 26a and teeth 27a remain at the clamped position. It will be noted that the degree of clamping may be adjusted by rotation of gudgeon 30 in accordance with the nature and the diameter of the strings to be clamped. Any damage to the strings may thus be avoided.

The operation of the machine described is as follows:

The frame A (FIG. 1) of the tennis racket to be strung is first secured onto the cradle 19-19a by means of the clamps 20. The string, previously attached to the ratchet frame A, is threaded through a suitable pair of perforations of the frame and passed on the guide 5, and it is Wound several times on the drum 6, the operator having previously actuated the pedal of the machine in order to raise the counterweight 11, whereby the jaws 7a, 7b have been opened and the sector-shaped member swung towards the left in FIG. 1 (position of the jaws and of the sector-shaped member as illustrated in FIG. 3).

The operator may thus dispose the string between the jaws. He then releases the pedal to liberate the counterweight 11, which has for its result that the string is clamped between jaws 7a, 7b and that it is tensioned owing to the torque which the counterweight imparts to member 4 and which tends to rotate the latter clockwise in FIG. 1. The parts thus assume the position illustrated in FIGS. 1 and 2. In these figures the string element under consideration is parallel to the major axis of the racket frame and it forms therefore what may be called a vertical element of the stringing.

The operator then rotates arm 22 (if necessary) so as to bring the support 25 of the clamping device to the position of FIG. 1, i.e. under the end of the said vertical element nearest to the sector-shaped member -4. He raises support 25 and disposes the string in the recess formed by the bent portion of fingers 26a (FIGS. 8 and 9). He actuates lever 28 so as to clamp the string between the said fingers and teeth 27a. He then locks arm 22 by means of the locking nut 23 (FIG. 6). The vertical element being thus firmly retained by the clamping device, he may release the jaws 7a and 7b by means of the pedal, as aforementioned, without the element loosing tension, more particularly owing to the resiliency of arms 19 which have been slightly bent towards the right during the tensioning process and now act as blade springs tending to return the racket frame towards the left. The string is thus released between jaws 7a, 7b and the racket frame A (position of FIG. 3), and it may be threaded through the next pair of perforations of the frame for the realization of another vertical element of the stringing.

'In order to tension this next vertical element of the stringing by means of the sector-shaped member 4 and of the jaws 7a, 7b associated therewith, it is of course necessary to rotate through 180 the cradle 19, 19a together with the racket frame A. For this purpose lever 18 is actuated as indicated by the corresponding arrow in FIG. 4, so as to release the support 15 of the cradle (FIG. 6), the said lever 18 being thereafter operated in the reverse direction to lock support 15 together with the cradle and the racket frame at the new position (which is the position illustrated in FIG. 4). The string may be threaded through the next perforations to form the next vertical element of the stringing, and it may be clamped between jaws 7a, 7b and tensioned under the action of the counterweight, as above explained. The parts then assume the position illustrated in FIG. 5. The pedal has been actuated in order to open jaws 7a, 7b and to swing the sector-shaped member 4 towards the cradle (FIG. 3); then the string has been passed on guide 5, around drum 6 and between jaws 7a, 7b, and the pedal has been released to tension the string as indicated in FIG. 1. The support 25 of the clamping device may again be brought under the end portion of the new vertical element nearest to the sector-shaped member 4 and the operative cycle may be repeated.

For the realization of the transverse or horizontal elements of the stringing the cradle 19, 19a and the racket frame are merely disposed at with respect to the positions illustrated in FIGS. 2 and 4.

With the machine according to the invention the string ing of a racket frame may be easily and rapidly effected, all the elements of the stringing being evenly tensioned. Owing to the slidable mounting of arm 22 on support 15, the clamping device 26-27 of FIGS. 7-9 may always be brought close to the racket frame whatever may be the shape and the dimensions thereof. The elements of the stringing may be disposed at any orientation, as for instance diagonally, if desired.

I claim:

1. A machine for the stringing of tennis rackets having a frame provided with pairs of perforations for passage of a string which forms an element of stringing between the perforations of each pair, said machine comprising a main frame, a cradle rotatable on said main frame about a substantially vertical axis and on which the frame of the racket to be strung is fixed, means on said main frame to lock said cradle thereon, releasable string tensioning means carried by said main frame to grasp and to tension a string threaded through a pair of perforations of the racket frame supported by said cradle to form one element of the stringing of said racket, said means acting on the portion of said string exterior to said racket frame, a clamping device disposed below said racket frame to maintain said one element under tension when such string tensioning means are released, and means to adjustably secure said clamping device to said cradle, said cradle having a substantially fiat lower base situated below said racket frame mounted upon said cradle, said means to adjustably secure said clamping device to said cradle comprising a substantially flat horizontal arm carrying a substantially vertical member in which said clamping device is vertically adjustable, said flat arm being formed with an elongated aperture, an upwardly directed pin carried by said base substantially coaxially to the axis of rotation of said cradle, said pin having a screw-threaded upper end and a locking nut screwed on said pin.

2. In a machine as claimed in claim 1, said clamping device having a depending tail portion and said vertical member of said flat arm being in the form of a socket to adjustably receive said tail portion.

3. A machine for the stringing of tennis rackets having a frame provided with pairs of perforations for passage of a string which forms an element of the stringing between the perforations of each pair, said machine comprising a main frame, a cradle rotatable on said main frame about a substantially vertical axis and on which the frame of the racket to be strung is fixed, means on said main frame to lock said cradle thereon, releasable string tensioning means carried by said main frame to grasp-and to tension a string threaded through a pair of perforations of the racket frame supported by said cradle to form one element of the stringing of said racket, said means acting on the portion of said string exterior to said racket frame, a clamping device disposed below said racket frame supported by said cradle to act on said one element close to said racket frame to maintain said one element under tension when said string tensioning means are released, and means to adjustably secure said clamping device to said cradle, said cradle comprising a substantially flat base, two substantially vertically upstanding arms secured to said base in diametrically opposed relation with respect to the vertical axis of rotation of said cradle on said main frame, and means at the upper end of said upstanding arms to support the frame of a racket to be strung substantially in a horizontal plane, said upstanding arms being sufiiciently resilient to flex laterally and to act as tension retaining spring means when the string attached to the racket frame is tensioned, said base having a radially protruding circular flange, said main frame having a substantially vertical bore in the vicinity of said flange and said means to lock said cradle on said main frame comprising a substantially vertical gudgeon slidable through said bore of said main frame, said gudgeon being formed with a lateral notch for passage of said flange therethrough and with a screw-threaded lower end which protrudes below said main frame, and a nut screwed on said screw-threaded lower end of said gudgeon to urge the same downwardly.

4. A machine for the stringing of tennis rackets having a frame provided with pairs of perforations for passage of a'string which forms an element of stringing between the perforations of each pair, said machine comprising a main frame, a cradle rotatable on said main frame about a substantially vertical axis and on which the frame of the racket to be strung is fixed, means on said main frame to lock said cradle thereon, releaseable string tensioning means carried by said main frame to grasp and to tension a string threaded through a pair of perforations of the racket frame supported by said cradle to form one element of the stringing of said racket, said means acting on the portion of said string exterior to said racket frame, a clamping device disposed below said racket frame supported by said cradle to act on said one element close to said racket frame to maintain said one element under tension when said string tensioning means are released, and means to adjustably secure said clamping device to said cradle, said clamping device comprising a support formed with a number of substantially parallel upstanding fingers having their ends bent at substantially in the form of downwardly opening hooks disposed along a substantially horizontal line to receive the tensioned element to be clamped, a movable member vertically displaceable on said support, said member being formed with a number of vertical teeth each to engage the bent portion of one of said fingers, and means on said support to actuate said movable member.

5. In a machine as claimed in claim 4, said actuating means being in the form of an adjustable rod-and-lever gearing forming an overcenter mechanism.

'6. A machine for the stringing of tennis rackets having a frame provided with pairs of perforations for passage of a string which forms an element of the stringing between the perforation of each pair, said machine comprising a main frame, a cradle rotatable on said main frame about a substantially vertical axis and on which the frame of the racket to be strung is fixed, means on said main frame to lock said cradle thereon, releasable string tensioning means carried by said main frame to grasp and to tension a string threaded through a pair of perforations of the racket frame supported by said cradle to form one element of the stringing of said racket, said means acting on the portion of said string exterior to said racket frame, a clamping device disclosed below said racket frame supported by said cradle to act on said one element close to said racket frame to maintain said one element under tension when said string tensioning means are released and means to adjustably secure said clamping device to said cradle, said string tensioning means comprising a swingable member pivoted to said main frame about a substantially horizontal axis, means on said swingable member to guide the string to be tensioned, a drum carried by said swingable member and on which said string may be wound to be frictionally retained thereon, a first jaw rigidly secured to said swingable member, a second jaw pivoted to said swingable member to cooperate with said first jaw to clamp said string beyond said drum, a rod pivoted to said second jaw to rotate same and also to rotate said swingable member through said second jaw, counter-weight means acting on said rod to cause same to close said second jaw against the first jaw to clamp said string beyond said drum and to rotate said swingable member in the proper direction to tension said string and means operable to raise such counter-weight means to relax the tension of said string and to liberate same from said first and second jaws.

References Cited UNITED STATES PATENTS 2,043,813 8/1936 Saladino 27373.l 2,309,849 2/ 1943 Kausal et al. 27.3-73.1

ANTON O. OECHSL'E, Primary Examiner T. BROWN, Assistant Examiner 

